Question: Orla and Eduardo each looked at a strand of their hair under a microscope and measured the diameter. Orla's strand was $0.005\,\text{cm}$ in diameter, and Eduardo's strand was $0.012\,\text{cm}$ in diameter. How much greater was the diameter of Eduardo's hair?
Solution: Eduardo's diameter $-$ Orla's diameter $=$ difference in diameter. $\begin{matrix} &&&&\\ &{0}.&0&1&2\\ -&{0}.&0&0&5\\ \hline &{0}.&0&0&7\\ \end{matrix}$ ${0}-{0}={0}$ The diameter of Eduardo's hair was $0.007\,\text{cm}$ greater than the diameter of Orla's hair.